InvalidDefinition

The start field that was refused.

not_allowed: a tool or model key outside what the template allows (allowed lists it), or instructions, tools or model on an agent that isn't dynamic. invalid: a repeated tool, instructions that are empty, over 16 KiB or hold the block's delimiter or sentence, or a label that is empty, over 64 characters, holds a control or format character, or is operator.

With not_allowed on tools or model: the names the template allows, so the model can correct itself. Absent otherwise.